// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: http://codemirror.net/LICENSE

// Because sometimes you need to style the cursor's line.
//
// Adds an option 'styleActiveLine' which, when enabled, gives the
// active line's wrapping <div> the CSS class "CodeMirror-activeline",
// and gives its background <div> the class "CodeMirror-activeline-background".

(function (mod) {
    if (typeof exports == "object" && typeof module == "object") // CommonJS
        mod(require("../../lib/codemirror"));
    else if (typeof define == "function" && define.amd) // AMD
        define(["../../lib/codemirror"], mod);
    else // Plain browser env
        mod(CodeMirror);
})(function (CodeMirror) {
    "use strict";
    var WRAP_CLASS = "CodeMirror-activeline";
    var BACK_CLASS = "CodeMirror-activeline-background";

    CodeMirror.defineOption("styleActiveLine", false, function (cm, val, old) {
        var prev = old && old != CodeMirror.Init;
        if (val && !prev) {
            cm.state.activeLines = [];
            updateActiveLines(cm, cm.listSelections());
            cm.on("beforeSelectionChange", selectionChange);
        } else if (!val && prev) {
            cm.off("beforeSelectionChange", selectionChange);
            clearActiveLines(cm);
            delete cm.state.activeLines;
        }
    });

    function clearActiveLines(cm) {
        for (var i = 0; i < cm.state.activeLines.length; i++) {
            cm.removeLineClass(cm.state.activeLines[i], "wrap", WRAP_CLASS);
            cm.removeLineClass(cm.state.activeLines[i], "background", BACK_CLASS);
        }
    }

    function sameArray(a, b) {
        if (a.length != b.length) return false;
        for (var i = 0; i < a.length; i++)
            if (a[i] != b[i]) return false;
        return true;
    }

    function updateActiveLines(cm, ranges) {
        var active = [];
        for (var i = 0; i < ranges.length; i++) {
            var range = ranges[i];
            if (!range.empty()) continue;
            var line = cm.getLineHandleVisualStart(range.head.line);
            if (active[active.length - 1] != line) active.push(line);
        }
        if (sameArray(cm.state.activeLines, active)) return;
        cm.operation(function () {
            clearActiveLines(cm);
            for (var i = 0; i < active.length; i++) {
                cm.addLineClass(active[i], "wrap", WRAP_CLASS);
                cm.addLineClass(active[i], "background", BACK_CLASS);
            }
            cm.state.activeLines = active;
        });
    }

    function selectionChange(cm, sel) {
        updateActiveLines(cm, sel.ranges);
    }
});
